“I’ve made some really great friends on Doctor Who over the years. Many of them,” he boasted. “And that is what I get to take away. And that, I suppose, as it always is, is the very best thing about anything—the people you meet.”

A lifelong fan of the BBC show, Moffat took over for Russell T. Davies in 2009, introducing Matt Smith as the Eleventh Doctor. Six seasons of complex plot arcs and shock-and-awe reveals later; there is still one incident that plagues the Scotsman.

“There’s loads of things I’d change. I’d change all my mistakes,” he said. “But that would be exhausting. [So] I’ll choose one mistake because it just rankles me to this day that I got this wrong.”

Remember the scene at the end of season five episode “Flesh and Stone,” when Amy comes on to the Doctor (goes as far as to kiss him)—the night before she’s set to marry the most wonderful man alive, Rory Williams?

“It’s a very good idea. Because she’s been going through this traumatic experience,” Moffat said of the conclusion to a two-part story featuring the Weeping Angels. “She doesn’t quite know who or what the Doctor is, and she doesn’t quite know what his interest is.

“There’s a brilliant scene to be written there, and I entirely avoided writing it,” he admitted. “I played it for laughs. And it was so wrong.”

Barely two when William Hartnell’s First Doctor debuted in 1963, Moffat’s first solo Doctor Who work—short story “Continuity Errors”—was published in 1996. Three years later, he scripted the parody Doctor Who and the Curse of the Fatal Death for Comic Relief’s Red Nose Day charity telethon.

In 2004, he was tapped to write for the revival of the classic program, penning award-winning scripts “The Empty Child,” “The Doctor Dances,” “The Girl in the Fireplace,” and “Blink.”

The eleventh season of Doctor Who is slated to begin in 2018. But what does the future hold for the long-running BBC program?

“This show will continue in whatever form the future holds for us, for as long as people want stories. I believe that, absolutely,” according to Moffat. “Just as King Arthur keeps going. Just as Robin Hood keeps going. Doctor Who will always be there.

“You take it off the air for 16 years, and it comes back as the big issue on television, there isn’t anything you can do to this show,” he said with a laugh. “Doctor Who goes on forever. It is more than a TV program; it is more than a story, it is actually a legend.”